One of the methods employed in the past to image the blood pool for diagnostic purposes involves the intravenous administration of 99m Tc serum albumin which is available commercially and is a sterile pyrogen-free solution of albumin labelled with Technetium 99m having an activity of greater than 100 microcuries/ml.
In utilizing this method of blood pool imaging, it is important to predose the patient immediately prior to the attempted visualization of the blood pool, since the 99m Tc serum albumin is very rapidly lost from the blood stream by exchange in the kidney.
Another method used in the past for imaging blood pools is the in vitro labelling of red blood cells (outside the host animal) followed by reinjection of the cells into the vascular system of the selected animal. By this method, it is possible to visualize both heart blood pools plus major peripheral vessels up to 3 hours after injection of the labelled cells. As can be seen, this is a complicated procedure, and therefore is a more time-consuming and expensive method.
Still another procedure for imaging blood involves the injection of stannous pyrophosphate followed by injection of 99m Tc-pertechnetate. This technique is reported as successful in producing satisfactory imaging of blood pools.